Understanding the Mechanical Response of Friction Stir Welded In Situ Processed Aluminum Alloy Metal Matrix Composite: Experimental and Statistical Modelling Approaches

This paper presents the results of a recent study on the effectiveness of the stir casting technique using the method of mixed salt route method and the subsequent joining of the in situ titanium diboride particulate reinforced aluminum alloy metal matrix composites using the technique of friction stir butt welding. A bimetallic flame-hardened friction stir welding tool with a threaded titanium probe and having different shoulder geometries were used for this novel research study. The variation in process parameters to include tool shoulder geometry, tool rotational speed, and welding speed does exert an influence on mechanical properties of the welded composite sample to include ultimate tensile strength, elongation, and microhardness. A noticeable change in the grain morphology coupled with refinement and near-uniform redistribution of the reinforcing particulates was observed using the titanium weld probe for all of the experiments. Microstructural characterization studies were conducted using a high-resolution scanning electron microscope and X-ray diffraction analysis. A statistical model and appropriate optimization technique were used to evaluate and/or interpret the mechanical response of the friction-stir welded joint. A substantial improvement in properties of the joint was observed in comparison with the base metal.